CN114859017B - Stratum stress field and displacement field control test device and method - Google Patents

Abstract

The invention discloses a stratum stress field and displacement field control test device which comprises a guide rail device, a model box, a loading frame, a model box hoisting device and a control system, wherein the guide rail device comprises a lifting guide rail which is arranged in the loading frame and can be lifted up and down and a fixed guide rail which is arranged outside the loading frame and can be connected with the lifting guide rail, and the model box hoisting device is matched with the guide rail device to be used for pulling the model box into or out of the loading frame. The invention also discloses a test method based on the stratum stress field and displacement field control test device. The invention has the beneficial effects that: by realizing the free switching of the control modes of the stress field and the displacement field, the test requirements of researching the mechanical response rule and the damage evolution rule of the underground structure under the action of various loads such as near-access engineering construction load, tunnel longitudinal differential settlement, earthquake and the like are met.

Description

Stratum stress field and displacement field control test device and method

Technical Field

The invention relates to the technical field of civil engineering tests, in particular to a device and a method for controlling and testing a stratum stress field and a stratum displacement field.

Background

The underground structure may be subjected to various load effects which are difficult to consider in the design stage in the whole life period, such as proximity engineering construction load, longitudinal uneven settlement of a tunnel, earthquake and the like. Wherein, the proximity engineering construction load refers to additional soil and water pressure applied to the existing underground structure by engineering constructions such as proximity foundation pit excavation, proximity shield tunneling and the like, and the load mainly comes from the change of a ground stress field; the longitudinal uneven settlement of the tunnel mainly originates from uneven deformation of a horizontal stratum under the tunnel, namely uneven change of a stratum displacement field; the seismic load can cause the stratum to deform unevenly along the depth direction, and an additional load effect is exerted on the underground structure in a mode of changing a stratum displacement field. In a word, the loads exert a load effect on the underground structure in a mode of changing a stratum stress field or a displacement field, so that the problems of underground structure diseases such as concrete cracking, joint opening, water leakage and the like are easily caused, and even serious consequences such as main bearing member damage, integral structure collapse and the like are caused. Therefore, it is necessary to simulate the changes of the formation stress field and the displacement field through a model test, obtain the mechanical response rule and the damage evolution rule of the underground structure, make a structure safety improvement measure according to the test result, and ensure the safety of the whole life cycle of the underground structure.

At present, a large-scale stratum-structure model test device is an effective means for realizing the control of a stratum stress field or a displacement field. In the aspect of stress field control, a true triaxial loading mode is usually adopted to simulate a tunnel three-dimensional ground stress field, namely a plurality of jacks are arranged in three directions for synchronous loading; in terms of displacement field control, a two-dimensional formation displacement field is usually simulated by using a laminar shear box, i.e. a plurality of actuators are arranged in the vertical direction to control the horizontal displacement of the formation layer by layer.

In order to evaluate the safety of the underground structure in the whole life cycle, it is necessary to simulate single or combined loading working conditions of multiple loads such as near engineering construction load, tunnel longitudinal uneven settlement, earthquake and the like, and the device is required to have the function of freely switching stress field and displacement field control modes. However, due to different research purposes, the two types of devices usually only have one capability of stress field control or displacement field control, and the test requirements of the combined loading working condition cannot be met. Therefore, a large-scale stratum-structure model test device capable of freely switching control modes of a stress field and a displacement field is urgently needed to meet the test requirements of researching mechanical response rules and damage evolution rules of underground structures under the action of various loads such as near-access engineering construction load, tunnel longitudinal uneven settlement, earthquakes and the like, and structural safety improvement measures are formulated according to test results, so that the full life cycle safety of the underground structures is guaranteed.

Disclosure of Invention

The invention discloses a stratum stress field and displacement field control test device and method, which meet the test requirements of researching the mechanical response rule and damage evolution rule of underground structures under the action of various loads such as near-access engineering construction load, tunnel longitudinal uneven settlement, earthquake and the like by realizing the free switching of the stress field and displacement field control modes, thereby effectively solving the technical problems related to the background technology.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a stratum stress field and displacement field control test device comprises a guide rail device, a model box, a loading frame, a model box hoisting device and a control system, wherein the guide rail device comprises a lifting guide rail which is arranged inside the loading frame and can be lifted up and down and a fixed guide rail which is arranged outside the loading frame and can be connected with the lifting guide rail, the model box hoisting device is matched with the guide rail device to be used for pulling the model box into or out of the loading frame, wherein,

the model box comprises a box body, a force transmission device arranged in the box body and rollers arranged at the bottom of the box body and rolling along the guide rail device, the box body comprises a top plate, a bottom plate opposite to the top plate and arranged at intervals and side plates connected with the top plate and the bottom plate, the side plates comprise a front side plate, a rear side plate opposite to the front side plate and arranged at intervals, and a left side plate and a right side plate connected with the front side plate and the rear side plate and arranged at intervals, loading holes for assembling the force transmission device are arranged on the top plate, the left side plate and the right side plate in a penetrating mode, part of the loading holes in the left side plate and the right side plate are arranged at equal intervals along the axis of the box body, the rest loading holes in the left side plate and the right side plate are arranged at equal intervals close to the front side plate end in a matrix mode, and detachable round doors are arranged on the front side plate and the rear side plate;

the loading frame comprises a bearing frame, a main cross beam and an actuator, the main cross beam is arranged on the inner side surface of the bearing frame, and the actuator is arranged on the main cross beam and is matched with the force transmission device to apply acting force to the force transmission device;

the control system is coupled to the actuator to control the force or displacement of the actuator.

As a preferable improvement of the present invention, the force transmission device comprises a force transmission rod inserted into the loading hole and a loading plate fixedly arranged on the force transmission rod and located in the box body.

As a preferable improvement of the present invention, the bottom surface of the top plate is provided with guide beams for guiding the movement of the force transfer devices and avoiding mutual interference between the force transfer devices along the long side directions of the opposite sides.

As a preferred improvement of the invention, the force transfer device comprises a vertical force transfer device fitted to the loading holes on the top plate and horizontal force transfer devices fitted to the loading holes on the left and right side plates, and the actuators comprise a vertical actuator cooperating with the vertical force transfer device and a horizontal actuator cooperating with the horizontal force transfer device.

As a preferred improvement of the invention, the model box further comprises a partition device which is installed in the box body and is used for ensuring that the soil body does not laterally deform in the front-rear direction, the partition device comprises a partition plate, a top pushing plate and a top pushing rod which is connected with the partition plate and the top pushing plate, the partition plate is connected with the left side plate, the right side plate and the bottom plate, and the top pushing plate is installed on the inner side wall of the rear side plate.

As a preferable improvement of the present invention, the lifting guide rail includes a liftable guide rail beam and a lifting cylinder for driving the guide rail beam to lift, and the control system is connected to the lifting cylinder to control the lifting cylinder.

As a preferable improvement of the present invention, the mold box lifting device includes a front lifting device mounted at the end of the fixed guide rail and a rear lifting device mounted outside the bearing frame.

As a preferable improvement of the invention, the front hoisting device and the rear hoisting device both comprise two L-shaped support rods connected with the fixed guide rail or the bearing frame and hoisting rods located between the two L-shaped support rods and used for mounting the chain block.

The invention also provides a test method based on the stratum stress field and displacement field control test device, which is applied to a single loading test under a longitudinal section working condition and comprises the following steps:

step one, completely lifting a lifting guide rail through a control system, and pulling a model box to a positioning block of a fixed guide rail by using a chain block arranged on a front hoisting device;

step two, respectively opening the detachable round door and the top plate on the front side plate and the rear side plate;

step three, opening loading holes arranged on the left side plate and the right side plate along the axis of the box body, and sealing the other loading holes by using sealing circular covers;

step four, mounting a horizontal force transmission device at the unsealed loading hole, and simultaneously mounting a horizontal actuator matched with the horizontal force transmission device on the main cross beam;

embedding the soil body, the underground structure reduced scale model and the related sensor into the box body until the soil body is embedded to be flush with the bottom surface of the guide beam, and leading out a sensor wire from the round doors of the front side plate and the rear side plate;

placing a rubber force transmission pad on the surface of a soil body, and then installing a top plate;

step seven, pulling the model box to a positioning block of the lifting guide rail by using a chain block arranged on the rear hoisting device, and then completely lowering the lifting guide rail to ensure that the model box is completely positioned in the loading frame;

step eight, connecting an actuator with a dowel bar of a force transmission device;

step nine, opening an electro-hydraulic servo oil source, a cooling system and a control system;

tenthly, designating the horizontal loading direction of the test device as the vertical direction of the actual ground stress field, and designating the vertical loading direction as the horizontal direction of the actual ground stress field;

step eleven, setting all the actuators to be in a force control mode in control software according to initial stress distribution on the model boundary, and specifying target force and loading time of each actuator;

step twelve, loading starting force, and simultaneously collecting test data until the initial ground stress loading stage is completed;

step thirteen, switching the horizontal actuator into a displacement control mode in control software, appointing the target displacement size and the loading time of the horizontal actuator according to a stratum settlement curve on the boundary of the model, and simultaneously keeping the vertical actuator as a force control model and keeping the force size unchanged;

step fourteen, starting displacement loading, and simultaneously acquiring test data until the loading stage of longitudinal differential settlement of the tunnel is completed;

fifthly, force and displacement of all the actuators are reset to zero, after the actuators are stabilized, the electro-hydraulic servo oil source, the cooling system and the control system are closed, and the connection between the actuators and the force transmission rods is released;

sixthly, completely lifting the lifting guide rail, pulling the model box to a positioning block of the fixed guide rail by using a chain block arranged on the front lifting device, and completely moving the model box out of the loading frame;

seventhly, opening the top plate, and sequentially moving out the rubber force transmission pad, the soil body and the underground structure reduced scale model;

eighteen, closing the top plate and the detachable circular door, and finishing the test.

The invention also provides a test method based on the stratum stress field and displacement field control test device, which is applied to a combined loading test under the cross section working condition and comprises the following steps:

step one, completely lifting a lifting guide rail through a control system, and pulling a model box to a positioning block of a fixed guide rail by using a chain block arranged on a front hoisting device;

step two, respectively opening the detachable round door and the top plate of the front side plate;

step three, opening the loading holes which are equidistantly arranged on the left side plate and the right side plate in a matrix form, and sealing the other loading holes by using sealing circular covers;

step four, mounting a horizontal force transmission device at the unsealed loading hole, and simultaneously mounting a horizontal actuator matched with the horizontal force transmission device on the main cross beam;

fifthly, installing a partition device in the box body;

embedding the soil body, the underground structure reduced scale model and the related sensor into a box body space between the front side plate and the partition plate until the soil body is embedded to be flush with the bottom surface of the guide beam, and leading out the wires of the sensor from the round door of the front side plate;

step seven, placing a rubber force transmission pad on the surface of the soil body, and then installing a top plate;

step eight, pulling the model box to a positioning block of the lifting guide rail by using a chain block arranged on the rear hoisting device, and then completely lowering the lifting guide rail to ensure that the model box is completely positioned in the loading frame;

step nine, connecting an actuator and a dowel bar;

step ten, opening an electro-hydraulic servo oil source, a cooling system and a control system;

step eleven, designating the horizontal loading direction of the test device as the horizontal direction of the actual ground stress field, and designating the vertical loading direction as the vertical direction of the actual ground stress field;

step twelve, setting all actuators as force control modes in control software according to initial stress distribution on the model boundary, and specifying target force and loading time of each actuator;

step thirteen, loading starting force, and simultaneously acquiring test data until the initial ground stress loading stage is completed;

step fourteen, according to the ground stress distribution after the excavation and unloading of the foundation pit, the target force magnitude and the loading time of each actuator after the unloading are specified in control software;

fifthly, loading starting force, and simultaneously acquiring test data until the foundation pit excavation unloading stage is completed;

sixthly, switching the horizontal actuator into a displacement control mode in control software, appointing the target displacement size and the loading time of the horizontal actuator according to a maximum stratum horizontal displacement curve caused by an earthquake on the boundary of the model, and simultaneously keeping the vertical actuator as a force control model with the force unchanged;

seventhly, starting displacement loading, and simultaneously acquiring test data until the earthquake load loading stage is completed;

eighteen, the forces and displacements of all the actuators are reset to zero, after the actuators are stabilized, the electro-hydraulic servo oil source, the cooling system and the control system are closed, and the connection between the actuators and the force transmission rod is released;

nineteenth, completely lifting the lifting guide rail, pulling the model box to a positioning block of the fixed guide rail by adopting a chain block arranged on the front hoisting device, and completely moving the model box out of the loading frame;

twenty, opening the top plate, and sequentially moving out the rubber force transmission pad, the soil body and the underground structure reduced scale model;

and twenty one, closing the top plate and the detachable circular door, and finishing the test.

The invention has the following beneficial effects:

1. the force and displacement control of the actuator is switched through the control system, the free switching of the control modes of the stress field and the displacement field is realized, the method can be used for carrying out a single loading test or a combined loading test under the working condition of a cross section or a longitudinal section, and is suitable for simulating various loading effects such as near-access engineering construction load, tunnel longitudinal uneven settlement, earthquake and the like, so that the mechanical response rule and the damage evolution rule of the underground structure under various loading effects are researched;

2. the switching between the cross section working condition mode and the longitudinal section working condition mode can be realized by assembling and disassembling the partition device and changing the arrangement mode of the force transmission device and the actuator, so that a single loading test or a combined loading test under the cross section or longitudinal section working condition can be carried out.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:

FIG. 1 is a schematic side view of the overall structure of a formation stress field and displacement field control test device in a longitudinal section working condition mode;

FIG. 2 is a schematic front view of the overall structure of the formation stress field and displacement field control test device in the longitudinal section mode;

FIG. 3 is a schematic side view of the overall structure of the formation stress field and displacement field control test device of the present invention in a cross-sectional mode;

FIG. 4 is a schematic front view of the overall structure of the formation stress field and displacement field control test device of the present invention in a cross-sectional mode;

FIG. 5 is a schematic view of the external structure of a model box under a longitudinal section working condition mode according to the present invention;

FIG. 6 is a schematic view of the internal structure of a model box under a longitudinal section working condition mode according to the present invention;

FIG. 7 is a schematic view of the external structure of the mold box in cross-section mode according to the present invention;

FIG. 8 is a schematic view of the internal structure of the mold box in cross-sectional mode according to the present invention;

FIG. 9 is a schematic view of the track arrangement of the present invention;

FIG. 10 is a structural frame diagram of the hydraulic system of the present invention;

FIG. 11 is a block diagram of the control system architecture of the present invention;

FIG. 12 is a schematic view of the partition structure of the present invention;

fig. 13 (a) and 13 (b) are a side view structural schematic diagram and a front view structural schematic diagram of the model box hoisting device provided by the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

It should be noted that all directional indicators (such as up, down, left, right, front, back \8230;) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise explicitly stated or limited, the terms "connected", "fixed", and the like are to be understood broadly, for example, "fixed" may be fixedly connected, may be detachably connected, or may be integrated; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of the technical solutions by those skilled in the art, and when the technical solutions are contradictory to each other or cannot be realized, such a combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

Referring to fig. 1-8, the present invention provides a formation stress field and displacement field control test apparatus, which includes a guide rail apparatus 1, a model box 2, a loading frame 3, a model box hoisting apparatus 4 and a control system, and referring to fig. 9, the guide rail apparatus 1 includes a lifting guide rail 11 installed inside the loading frame 3 and capable of lifting up and down, and a fixed guide rail 12 installed outside the loading frame 3 and capable of connecting with the lifting guide rail 11, the ends of the lifting guide rail 11 and the fixed guide rail 12 are both provided with a positioning block 110, and the positioning block 110 is used to ensure that the model box 2 is positioned correctly inside and outside the loading frame 3.

Specifically, the lifting guide rail 11 comprises a lifting guide rail beam 111 and a lifting cylinder 112 for driving the lifting guide rail beam 111 to lift, and the control system is connected with the lifting cylinder 112 to control the lifting cylinder 112 to realize the lifting control of the guide rail beam 111, so that when the guide rail beam 111 is lifted, the guide rail beam 111 is connected with the fixed guide rail 12 for transporting the model box 2 into the loading frame 3; when the guide rail beam 111 is lowered and is separated from the fixed guide rail 12, the model box 2 is lowered together with the guide rail beam 111, and when the guide rail beam 111 is completely lowered, the model box 2 is supported by the loading frame 3 and suspended, so that the sliding of the model box 2 during the loading process can be avoided.

The mold box 2 comprises a box body 21, a force transmission device 22 mounted on the box body 21, and a roller 23 mounted on the bottom of the box body 21 and rolling along the rail device 1.

The box body 21 includes a top plate 211, a bottom plate 212 opposed to the top plate 211 and spaced apart from each other, and side plates 213 connecting the top plate 211 and the bottom plate 212, and the side plates 213 include a front side plate 2131, a rear side plate 2132 opposed to the front side plate 2131 and spaced apart from each other, and a left side plate 2133 and a right side plate 2134 opposed to the front side plate 2131 and the rear side plate 2132 and spaced apart from each other.

The bottom surface of the top plate 211 is provided with guide beams 214 along the longitudinal direction of the opposite sides for guiding the movement of the force transfer device 22 and avoiding interference between the force transfer devices 22.

The top plate 211, the left side plate 2133 and the right side plate 2134 are all provided with loading holes 215 for assembling the force transmission device 22 in a penetrating manner, and the loading holes 215 are also provided with sealing round covers 217 in a matching manner. The partial loading holes 215 on the left and right side plates are equidistantly arranged along the axis of the box body 21 and the remaining loading holes on the left and right side plates are equidistantly arranged in a matrix form near the end of the front side plate 2131. Specifically, the loading holes 215 for the cross-section mode are equidistantly arranged in a matrix near the front side plate end, and the loading holes 215 for the longitudinal section mode are equidistantly arranged along the tank axis.

Specifically, the force transmission device 22 includes a dowel 221 inserted into the loading hole 215, and a loading plate 222 fixed to the dowel 221 and located in the box 21. Further, the force transfer device 22 comprises a vertical force transfer device 223 fitted to the loading hole 215 of the top plate 211 and a horizontal force transfer device 224 fitted to the loading hole 215 of the left side plate 2133 and the right side plate 2134.

The loading plate 222 of the horizontal force transfer device 224 may be divided into a large-sized horizontal loading plate and a small-sized horizontal loading plate, which are used for the longitudinal section mode and the transverse section mode, respectively. The loading plate 222 of the vertical force transfer device 223 is in contact with the guide beam 214 through a pulley, and the loading plate 222 of the horizontal force transfer device 224 is spaced from the bottom surface of the guide beam 214.

Further, the vertical force transmission device 223, the guide beam 214 and the top plate 211 are integrally arranged, so that the top plate 211 can be conveniently mounted and dismounted.

Furthermore, the dowel bar 221 and the loading plate 222 of the horizontal force transmission device 224 are detachably designed, so that different working condition modes can be switched conveniently.

Further, the front side plate 2131 and the rear side plate 2132 are provided with detachable round doors 216, which can be used for directly observing the model status in the box body 21 to avoid the occurrence of dangerous situations.

Referring to fig. 12 again, the model box 2 further includes a partition device installed in the box body 21 for ensuring that the soil body is not deformed laterally in the front-rear direction, i.e. ensuring that the model is in a plane strain state. The partition device comprises a partition board 251, a top push board 252 and a top push rod 253 connecting the partition board 251 and the top push board 252, wherein the partition board 251 is connected with a left side board 2133, a right side board 2134 and a bottom board 212, and the top push board 252 is installed on the inner side wall of the rear side board 2132.

It should be further noted that when the partition device is not installed, the test device is in a longitudinal section working condition mode, and all spaces in the box body 21 are used for filling a stratum-structure model; during installation, the test device is in a cross section working condition mode, and at the moment, only part of the space in the box body 21 close to the front side plate 2131 is used for filling a stratum-structure model.

In fact, in order to transmit the force to the soil 7 uniformly, a rubber force transmission pad 225 is further disposed between the surface of the soil 7 and the loading plate 222 of the vertical force transmission device 223, the width of the rubber force transmission pad is slightly smaller than the horizontal interval between the two guide beams 214, and the thickness and length of the rubber force transmission pad are consistent with the length of the box body 21 in the longitudinal section working mode and consistent with the distance from the inner wall of the front side plate 2131 to the inner wall of the partition plate 251 in the transverse section working mode.

The loading frame 3 includes a bearing frame 31, three main beams 32 and an actuator 33, the main beams 32 are disposed on the inner side surface of the bearing frame 31, specifically, the number of the main beams 32 is three, one main beam 32 is fixedly disposed on the bottom surface of the top wall of the bearing frame 31, the remaining two main beams 32 are disposed in parallel at intervals and are respectively disposed on the inner side surfaces of the two opposite side walls of the bearing frame 31, the lifting guide rail 11 is mounted at the bottom of the bearing frame 31, so that after the lifting guide rail 11 is completely lowered, the model box 2 is supported by the bearing frame 31, and the rollers 23 at the bottom of the model box 2 are suspended, thereby preventing the model box 2 from sliding in the loading process.

The actuator 33 is mounted on the main beam 32 and cooperates with the force transfer device 22 for applying a force to the force transfer device 22. In particular, the actuators 33 comprise a vertical actuator 331 cooperating with the vertical force transfer device 223 and a horizontal actuator 332 cooperating with the horizontal force transfer device 224. It is also to be construed that the actuators 33 perpendicular to the left and right side walls of the loading frame 31 are referred to as horizontal actuators 332, and the actuators 33 perpendicular to the top wall are referred to as vertical actuators 331.

Further, the actuators 33 are installed on the main beam 32, and are concentrically corresponding to the loading holes 215 of the model box 2, and are connected with the loading plate 222 inside the model box 2 through the force transmission rod 221, so as to ensure that the resultant action points and directions of the actuators 33 and the loading plate 222 are consistent.

It should be further noted that the horizontal actuator 332 can be changed in installation position according to the operating mode. The bearing frame 3 is a self-reaction structure, the force applied by all the actuators 33 is balanced by the internal force of the frame, and the ground only bears the self weight of the equipment.

Referring again to fig. 13 (a) and (b), the mold box lifting device 4 includes a front lifting device mounted to the end of the fixed rail 12 and a rear lifting device mounted to the outside of the carrier 31. The front hoisting device and the rear hoisting device respectively comprise two L-shaped support rods 41 connected with the fixed guide rail 12 or the bearing frame 31 and two hoisting rods 42 positioned between the L-shaped support rods 41 and used for installing the chain block. The mold box hoisting device 4 is matched with the guide rail device through a chain block so as to be used for pulling the mold box 2 into or out of the loading frame 3.

The chain block is connected with the model box 2 through an iron chain, a lifting hook and a shackle. The chain block mounted on the front hoisting device is used for pulling the model box 2 out of the loading frame 3, and the chain block mounted on the rear hoisting device is used for pulling the model box 2 into the loading frame 3.

Referring to fig. 11, the testing apparatus further includes a hydraulic system, and the hydraulic system includes an electro-hydraulic servo oil source 61, a cooling system 62, an oil separator 63, and a hydraulic pipeline 64. The electro-hydraulic servo oil source 61 provides power oil for the actuator 33. The cooling system 62 is connected with the electro-hydraulic servo oil source 61 and is used for controlling the oil temperature in a proper temperature range. The electro-hydraulic servo oil source 61 and the cooling system 62 are installed and stored indoors, and maintenance and repair are facilitated. The oil separator 63 is used for establishing a connection between the electro-hydraulic servo oil source 61 and the actuators 33, providing independent control over the output flow and pressure of the oil source, and adapting to different operation requirements of each actuator 33. The hydraulic line 64 connects the electro-hydraulic servo oil source 61, the oil separator 63, and the actuator 33 together, and has a capability of withstanding high pressure.

Referring again to fig. 10, the control system is connected to the actuator 33 to control the force or displacement of the actuator 33. Specifically, the control system includes a computer 51 with control software installed, a multi-channel controller 52, and a sensor 53.

The computer 51 is connected to a multichannel controller 52, and commands for the force or displacement of each actuator 33 are given to the multichannel controller 52 by control software. The multichannel controller 52 is connected to the oil separator 63 through a control line to convert the command from the computer 51 into the oil pressure of the actuator 33, and is connected to the sensor 53 through a sensor signal line to realize closed loop control.

The sensor 53 includes a displacement sensor, a force sensor, and an oil pressure sensor, and is mounted on each actuator 33. Under closed loop control, the control system 5 controls the oil separator 63 to adjust the oil pressure of the actuator 33 to make the measured force or displacement equal to the computer command, thereby realizing the force or displacement control of the actuator 33. Thus, closed loop control can achieve synchronous, asynchronous force or displacement loading of all actuators 33.

Specifically, the control system 5 may simultaneously control each actuator 33 to be synchronously loaded to a corresponding specified force to simulate an initial ground stress field, and then control any one or more actuators 33 to be synchronously or step-by-step loaded to a corresponding specified force or displacement value according to a target boundary stress or displacement distribution form, thereby realizing free switching of stress field and displacement field control modes, and simulating multiple load effects such as a construction load of an approaching engineering, longitudinal uneven settlement of a tunnel, an earthquake and the like.

Example 1

The invention also provides a test method based on the stratum stress field and displacement field control test device, which is applied to a single loading test under a longitudinal section working condition and comprises the following steps:

step one, completely lifting a lifting guide rail 11 through a control system 5, and pulling a model box 2 to a positioning block 110 of a fixed guide rail 12 by using a chain block arranged on a front hoisting device;

step two, the detachable round door 216 and the top plate 211 on the front side plate and the rear side plate are respectively opened;

step three, opening the loading holes 215 arranged on the left side plate and the right side plate along the axis of the box body 21, and sealing the other loading holes 215 by using a sealing circular cover 217;

step four, installing a horizontal force transmission device 224 at the unsealed loading hole 215, and installing a horizontal actuator 332 matched with the horizontal force transmission device 224 on the main cross beam 32;

step five, burying the soil body 7, the underground structure scale model 8 and related sensors into the box body 21, and leading out sensor leads from circular doors 216 of the front side plate 2131 and the rear side plate 2132;

step six, placing a rubber force transmission pad 225 on the surface of a soil body, and then installing a top plate 211;

step seven, pulling the model box 2 to a positioning block 110 of the lifting guide rail 11 by using a chain block arranged on the rear hoisting device, and then completely lowering the lifting guide rail 11 to ensure that the model box 2 is completely positioned in the loading frame 3;

step eight, connecting the actuator 33 with a dowel bar 221 of the force transmission device 22;

step nine, opening the electro-hydraulic servo oil source 61, the cooling system 62 and the control system 5;

tenthly, designating the horizontal loading direction of the test device as the vertical direction of the actual ground stress field, and designating the vertical loading direction as the horizontal direction of the actual ground stress field;

step eleven, setting all the actuators 33 in a control software into a force control mode according to the initial stress distribution on the model boundary, and specifying a target force and a loading time of each actuator 33;

step twelve, loading starting force, and simultaneously collecting test data until the initial ground stress loading stage is completed;

thirteen, switching the horizontal actuator 332 into a displacement control mode in control software, appointing the target displacement size and the loading time of the horizontal actuator according to a stratum settlement curve on the boundary of the model, and simultaneously keeping the vertical actuator 331 as a force control model and keeping the force size unchanged;

fourteen, starting displacement loading, and simultaneously acquiring test data until the longitudinal differential settlement loading stage of the tunnel is completed;

step fifteen, force and displacement of all the actuators 33 are reset to zero, after the actuators 33 are stabilized, the electro-hydraulic servo oil source 61, the cooling system 62 and the control system 5 are closed, and connection between the actuators 33 and the dowel bars 221 is released;

sixthly, the lifting guide rail 11 is completely lifted, the chain block mounted on the front lifting device is used for pulling the model box 2 to the positioning block 110 of the fixed guide rail 12, and the model box 2 is completely moved out of the loading frame 3;

seventhly, opening the top plate 211, and sequentially moving out the rubber force transmission pad 225, the soil body 7 and the underground structure reduced scale model 8;

eighteen, closing the top plate 211 and the detachable circular door 216, and finishing the test.

Example 2

The invention also provides a test method based on the stratum stress field and displacement field control test device, which is applied to a combined loading test under the cross section working condition and comprises the following steps:

step one, the lifting guide rail 11 is completely lifted through the control system 5, and the chain block arranged on the front hoisting device is used for pulling the model box 2 to the positioning block 110 of the fixed guide rail 12;

step two, respectively opening the detachable round door 216 and the top plate 211 of the front side plate;

step three, opening the loading holes 215 which are equidistantly arranged on the left side plate and the right side plate in a matrix form, and sealing the rest loading holes 215 by using a sealing circular cover 217;

step four, installing a horizontal force transmission device 224 at the unsealed loading hole 215, and installing a horizontal actuator 332 matched with the horizontal force transmission device 224 on the main cross beam 32;

step five, installing a partition device in the box body 21;

step six, embedding the soil body 7, the underground structure scale model 8 and related sensors into the space of the box body 21 between the front side plate 2131 and the partition plate 251 until the soil body is embedded to be flush with the bottom surface of the guide beam 214, and leading out leads of the sensors 53 from the round door 216 of the front side plate 2131;

placing a rubber force transmission pad 225 on the surface of the soil body, and then installing a top plate 211;

step eight, pulling the model box 2 to a positioning block 110 of the lifting guide rail 11 by using a chain block arranged on the rear hoisting device, and then completely lowering the lifting guide rail 11 to ensure that the model box 2 is completely positioned in the loading frame 3;

step nine, connecting the actuator 33 and the dowel bar 221;

step ten, opening the electro-hydraulic servo oil source 61, the cooling system 62 and the control system 5;

step eleven, designating the horizontal loading direction of the test device as the horizontal direction of the actual ground stress field, and designating the vertical loading direction as the vertical direction of the actual ground stress field;

step twelve, setting all the actuators 33 in a control software to be in a force control mode according to the initial stress distribution on the model boundary, and specifying the target force and the loading time of each actuator 33;

step thirteen, loading starting force, and simultaneously acquiring test data until the initial ground stress loading stage is completed;

step fourteen, according to the ground stress distribution after unloading in the foundation pit excavation, the target force size and the loading time of each actuator 33 after unloading are specified in the control software;

fifthly, loading starting force, and simultaneously acquiring test data until the foundation pit excavation unloading stage is completed;

sixthly, switching the horizontal actuator 332 into a displacement control mode in control software, appointing the target displacement size and the loading time of the horizontal actuator 332 according to a maximum stratum horizontal displacement curve caused by an earthquake on the boundary of the model, and simultaneously keeping the vertical actuator 331 as a force control model with the force size unchanged;

seventhly, starting displacement loading, and simultaneously acquiring test data until the earthquake load loading stage is completed;

eighteen, force and displacement of all the actuators 33 are reset to zero, after the actuators 33 are stabilized, the electro-hydraulic servo oil source 61, the cooling system 62 and the control system 5 are closed, and the connection between the actuators 33 and the dowel bars 221 is released;

nineteenth, the lifting guide rail 11 is completely lifted, then the chain block arranged on the front hoisting device is adopted to pull the model box 2 to the positioning block 110 of the fixed guide rail 12, and at the moment, the model box 2 is completely moved out of the loading frame 3;

step twenty, opening the top plate 211, and sequentially moving out the rubber force transmission pad 225, the soil body 7 and the underground structure reduced scale model 8;

and twenty one, closing the top plate 211 and the detachable circular door 216, and finishing the test.

The invention has the following beneficial effects:

1. the force and displacement control of the actuator can be switched through the control system, free switching of control modes of a stress field and a displacement field is realized, the method can be used for carrying out a single loading test or a combined loading test under a cross section or longitudinal section working condition, and is suitable for simulating multiple loading actions such as proximity engineering construction load, tunnel longitudinal uneven settlement, earthquake and the like, so that the mechanical response rule and the damage evolution rule of the underground structure under the action of multiple loads are researched;

2. the switching between the cross section working condition mode and the longitudinal section working condition mode can be realized by assembling and disassembling the partition device and changing the arrangement mode of the force transmission device and the actuator, so that a single loading test or a combined loading test under the cross section or longitudinal section working condition can be carried out.

While embodiments of the invention have been described above, it is not intended to be limited to the details shown herein, and to the particular embodiments shown, but it is to be understood that all changes and modifications that come within the spirit and scope of the invention are desired to be protected by the teachings herein.

Claims (8)

1. A stratum stress field and displacement field control test device is characterized by comprising a guide rail device, a model box, a loading frame, a model box hoisting device and a control system, wherein the guide rail device comprises a lifting guide rail which is installed inside the loading frame and can be lifted up and down and a fixed guide rail which is installed outside the loading frame and can be connected with the lifting guide rail, the model box hoisting device is matched with the guide rail device to be used for pulling the model box into or out of the loading frame, wherein,

the model box comprises a box body, a force transmission device installed on the box body and idler wheels installed at the bottom of the box body and rolling along the guide rail device, the box body comprises a top plate, a bottom plate opposite to the top plate and arranged at intervals and side plates connected with the top plate and the bottom plate, the side plates comprise a front side plate, a rear side plate opposite to the front side plate and arranged at intervals, and a left side plate and a right side plate connected with the front side plate and the rear side plate and arranged at intervals, loading holes used for assembling the force transmission device are arranged on the top plate, the left side plate and the right side plate in a penetrating mode, part of the loading holes in the left side plate and the right side plate are arranged at equal intervals along the axis of the box body and used for a longitudinal section working condition mode, the rest loading holes in the left side plate and the right side plate are arranged at equal intervals close to the front side plate end in a matrix mode and used for a cross section working condition mode, and detachable round doors are arranged on the front side plate and the rear side plate;

the force transmission device comprises a dowel bar inserted into the loading hole and a loading plate fixedly arranged on the dowel bar and positioned in the box body;

the loading frame comprises a bearing frame, a main cross beam and an actuator, the main cross beam is arranged on the inner side surface of the bearing frame, and the actuator is arranged on the main cross beam and is matched with the force transmission device to apply acting force to the force transmission device;

the control system is connected with the actuator to control the force or displacement of the actuator;

the model box also comprises a partition device which is arranged in the box body and is used for ensuring that the soil body does not generate lateral deformation in the front and rear directions, the partition device comprises a partition plate, a top push plate and a top push rod which is connected with the partition plate and the top push plate, the partition plate is connected with a left side plate, a right side plate and a bottom plate, and the top push plate is arranged on the inner side wall of the rear side plate; when the partition device is installed, the test device is in a cross section working condition mode, and at the moment, only part of space close to the front side plate in the box body is used for filling a stratum-structure model.

2. The formation stress field and displacement field control test device of claim 1, wherein the bottom surface of the top plate is provided with guide beams along the long side directions of the two opposite sides for guiding the movement of the force transfer devices and avoiding the mutual interference between the force transfer devices.

3. The formation stress field and displacement field control test device of claim 2, wherein the force transfer device comprises a vertical force transfer device assembled in the loading hole in the top plate and a horizontal force transfer device assembled in the loading hole in the left side plate and the right side plate, and the actuators comprise a vertical actuator cooperating with the vertical force transfer device and a horizontal actuator cooperating with the horizontal force transfer device.

4. The formation stress field and displacement field control test device of claim 1, wherein the lifting guide rail comprises a liftable guide rail beam and a lifting cylinder driving the guide rail beam to lift, and the control system is connected with the lifting cylinder to control the lifting cylinder.

5. The formation stress field and displacement field control test device of claim 1, wherein the model box hoisting device comprises a front hoisting device mounted at the tail end of the fixed guide rail and a rear hoisting device mounted outside the main beam.

6. The formation stress field and displacement field control test device of claim 5, wherein the front hoisting device and the rear hoisting device each comprise two L-shaped support rods connected with a fixed guide rail or a main beam and a hoisting rod located between the two L-shaped support rods and used for mounting a chain block.

7. A test method based on the stratum stress field and displacement field control test device of any one of claims 1 to 6 is characterized in that the test method is applied to a single loading test under a longitudinal section working condition and comprises the following steps:

step one, completely lifting a lifting guide rail through a control system, and pulling a model box to a positioning block of a fixed guide rail by using a chain block arranged on a front hoisting device;

step two, respectively opening the detachable round door and the top plate on the front side plate and the rear side plate;

step three, opening loading holes arranged on the left side plate and the right side plate along the axis of the box body, and sealing the other loading holes by using sealing circular covers;

step four, mounting a horizontal force transmission device at the unsealed loading hole, and simultaneously mounting a horizontal actuator matched with the horizontal force transmission device on the main cross beam;

embedding the soil body, the underground structure reduced scale model and the related sensor into the box body until the soil body is embedded to be flush with the bottom surface of the guide beam, and leading out a sensor wire from the round doors of the front side plate and the rear side plate;

placing a rubber force transmission pad on the surface of the soil body, and then installing a top plate;

step seven, pulling the model box to a positioning block of the lifting guide rail by using a chain block arranged on the rear hoisting device, and then completely lowering the lifting guide rail to ensure that the model box is completely positioned in the loading frame;

step eight, connecting an actuator with a dowel bar of a force transmission device;

step nine, opening an electro-hydraulic servo oil source, a cooling system and a control system;

tenthly, designating the horizontal loading direction of the test device as the vertical direction of the actual ground stress field, and designating the vertical loading direction as the horizontal direction of the actual ground stress field;

step eleven, setting all the actuators to be in a force control mode in control software according to initial stress distribution on the model boundary, and specifying target force and loading time of each actuator;

step twelve, loading starting force, and simultaneously collecting test data until the initial ground stress loading stage is completed;

step thirteen, switching the horizontal actuator into a displacement control mode in control software, appointing the target displacement size and the loading time of the horizontal actuator according to a stratum settlement curve on the boundary of the model, and simultaneously keeping the vertical actuator as a force control model with the force unchanged;

step fourteen, starting displacement loading, and simultaneously acquiring test data until the loading stage of longitudinal differential settlement of the tunnel is completed;

fifthly, force and displacement of all the actuators are reset to zero, after the actuators are stabilized, the electro-hydraulic servo oil source, the cooling system and the control system are closed, and the connection between the actuators and the force transmission rods is released;

sixthly, completely lifting the lifting guide rail, pulling the model box to a positioning block of the fixed guide rail by using a chain block arranged on the front hoisting device, and completely moving the model box out of the loading frame;

seventhly, opening a top plate, and sequentially moving out the rubber force transmission pad, the soil body and the underground structure reduced scale model;

eighteen, closing the top plate and the detachable circular door, and finishing the test.

8. A test method based on the formation stress field and displacement field control test device of any one of claims 1 to 6 is applied to a combined loading test under a cross-section working condition and comprises the following steps:

step one, completely lifting a lifting guide rail through a control system, and pulling a model box to a positioning block of a fixed guide rail by using a chain block arranged on a front hoisting device;

step two, respectively opening the detachable round door and the top plate of the front side plate;

step three, opening the loading holes which are equidistantly arranged on the left side plate and the right side plate in a matrix form, and sealing the other loading holes by using sealing circular covers;

step four, mounting a horizontal force transmission device at the unsealed loading hole, and simultaneously mounting a horizontal actuator matched with the horizontal force transmission device on the main cross beam;

fifthly, installing a partition device in the box body;

embedding the soil body, the underground structure reduced scale model and the related sensor into a box body space between the front side plate and the partition plate until the soil body is embedded to be flush with the bottom surface of the guide beam, and leading out leads of the sensor from a round door of the front side plate;

step seven, placing a rubber force transmission pad on the surface of the soil body, and then installing a top plate;

step eight, pulling the model box to a positioning block of the lifting guide rail by using a chain block arranged on the rear hoisting device, and then completely lowering the lifting guide rail to ensure that the model box is completely positioned in the loading frame;

step nine, connecting an actuator and a dowel bar;

step ten, opening an electro-hydraulic servo oil source, a cooling system and a control system;

step eleven, designating the horizontal loading direction of the test device as the horizontal direction of the actual ground stress field, and designating the vertical loading direction as the vertical direction of the actual ground stress field;

step twelve, setting all actuators as force control modes in control software according to initial stress distribution on the model boundary, and specifying target force and loading time of each actuator;

step thirteen, starting force loading, and simultaneously collecting test data until the initial ground stress loading stage is completed;

step fourteen, according to the ground stress distribution after unloading in the foundation pit excavation, the target force size and the loading time of each actuator after unloading are specified in control software;

fifthly, loading starting force, and simultaneously acquiring test data until the foundation pit excavation unloading stage is completed;

sixthly, switching the horizontal actuator into a displacement control mode in control software, appointing the target displacement size and the loading time of the horizontal actuator according to a maximum stratum horizontal displacement curve caused by an earthquake on the boundary of the model, and simultaneously keeping the vertical actuator as a force control model with the force unchanged;

seventhly, starting displacement loading, and simultaneously acquiring test data until the earthquake load loading stage is completed;

eighteen, force and displacement of all the actuators are reset to zero, after the actuators are stabilized, the electro-hydraulic servo oil source, the cooling system and the control system are closed, and the connection between the actuators and the force transmission rods is released;

nineteenth, the lifting guide rail is completely lifted, then the chain block arranged on the front hoisting device is adopted to pull the model box to the positioning block of the fixed guide rail, and at the moment, the model box is completely moved out of the loading frame;

twenty, opening the top plate, and sequentially moving out the rubber force transmission pad, the soil body and the underground structure reduced scale model;

and twenty one, closing the top plate and the detachable circular door, and finishing the test.

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